Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$143.85	10.303%	$158.6709	$158.67	$158.65	$158.70
Purchase #2	$86.85	13.439%	$98.5218	$98.52	$98.50	$98.50
Purchase #3	$149.52	7.598%	$160.8805	$160.88	$160.90	$160.90
Purchase #4	$91.84	9.298%	$100.3793	$100.38	$100.40	$100.40
Purchase #5	$211.64	5.387%	$223.041	$223.04	$223.05	$223.00
Purchase #6	$121.64	9.385%	$133.0559	$133.06	$133.05	$133.10
Purchase #7	$129.58	8.786%	$140.9649	$140.96	$140.95	$141.00
7 purchase totals =	$934.92		$1,015.5143	$1,015.51	$1,015.50	$1,015.60